Orion's 8" f/4 reflector promises to do double duty - it's both a wide-field medium aperture visual
telescope and a fast f/4 imaging
astrograph. It's attractively priced at only $449 and comes nicely
appointed with a precision 2 speed focuser, mounting rings, and a cooling fan in
the back. I've seen this scope at local star parties and have enjoyed
looking through it. I managed to snare it away from its owner for a few
weeks to put it through its paces. The 8" f/4 configuration has a
long tradition among astrophotographers, especially the Japanese. Vixen
made a similar looking R200SS model for years, and if you had the money, there
was always a Takahashi Epsilon 200 waiting for you. Orion's model comes in
well below the asking price of either and would seem to be a boon for budding
imagers, or for observers who like to do wide field observing.

Orion's 8" f/4 Newtonian Astrograph on a CG5 mount

The scope is sold as an optical tube assembly only. I
think it's assumed that anyone interested in this telescope will already have a
mount in mind before buying it. Just beware, the scope is bigger and
heavier than it looks in pictures. Orion lists the OTA weight at 16.5 lbs,
but I weighed the complete OTA with rings, dovetail plate, finder, and extension
tube at 20.3 lbs on my digital scale. In any
case, its weight will overpower CG4/Astroview
class mounts. I happened to have a Celestron CG5 (same as the Orion
Sky View Pro) handy but even it required two counterweights to balance out the
tube. The CG5 weighed in at 52 lbs. So, in total, you are looking at
a 70+ lb rig.

If weight is an issue and you're trying to decide between Orion's
6" f/5 and 8" f/4 astrographs, keep in mind that the 6" is going
to be a lot more manageable. Not only is the tube lighter (claimed 10 lbs vs. 16.5
lbs) it only needs one counterweight, and you might be able to get away with a
smaller mount entirely - something in the Sky View Deluxe or Great Polaris
category might work. A similarly
equipped 6" f/5 assembly could be as much as 20 lbs less.

Having said all that, as the weeks went on, I did more
proficient at picking the whole thing up. I didn't come close to any
disastrous mishaps, but I did find myself taking a deep breath before moving the
rig.

Close up of the focuser

Set up as seen here, the entire assembly will set you back about $850.
I'd consider this a minimum to get started. Add in a Paracorr, polar
alignment scope, Goto on the mount and other accessories, and you could easily
double that amount (there are no eyepieces included in the price.) I set
the scope up and went observing over several weeks in November and December of
2010. This turned out to be unusually cold and windy for this time of the
year.

There are few things that stand out right away as you use the scope visually.
First, the CG5 is more than enough to hold the short tube, even in windy
conditions. I get a little suspicious whenever small to medium sized
mounts need two counterweights, but I didn't have to worry here. Secondly,
although the tube is quite small (only 28" long) and balances just fine
along the right ascension axis with the two counterweights, it is a little
unbalanced along the declination axis. I mentioned this and the owner of
the scope says that sometimes he attaches magnetic weights on the back of the
tube opposite the side of the focuser. This solves the problem but it's a
little inelegant, and adds even more weight to the rig - the last thing you
need. Third, the rings
are really tight. You cannot rotate the tube in the rings unless
you undo the latches. Anyone who uses an equatorially-mounted Newtonian
will tell you that you wind up doing this a lot, especially as you swing the
scope from one side of the sky to the other. As the nights got longer, I
caught myself not viewing certain objects if they weren't in the
"right" part of the sky.

The scope comes with a two speed Crayford focuser. And what a focuser it
is! The hardware is extremely well-made, and it's got lots of dials, screws, knobs, adapters, and an 35 mm long
2" extension tube. I'm
pleasantly surprised to see it on such an inexpensive scope. I can picture
people buying the OTA just to get the focuser - it's that good. The
focuser does seem to be optimized for photography though, as you need lots of
out-focus travel to come to focus with most eyepieces. If you're using
eyepieces that take a lot of back-focus to begin with (like most of the TeleVues)
you cannot reach focus unless you use the 35 mm extension tube (shown above.)
Even then, the focuser wound up getting racked all the way out (and I mean ALL
the way out, right to the stop) to reach focus with most of my Panoptics. Check out the photo above; that's the actual focus position of
the 22 mm Panoptic. It's almost freakishly high off the tube.

Finally, the collimation screws work OK, but the mirror cell
isn't the greatest of designs. If you back off too much on one screw (or a
small amount on two screws) the mirror has a tendency to shift, causing you to
start all over again. The solution: as soon as you loosen one screw, be
sure and cinch up the remaining ones to keep pressure on the mirror.

Close up on the collimation screws and the fan assembly

I like my observing experiences to be
"transparent." Once the observing starts, I don't want to think
about the equipment. The telescope should be an extension of your mind and
body. Obviously, Goto systems usually succeed in this regard, as do most
nice Dobs - grab the tube and point. The Orion didn't quite pass with
flying colors here, as I had to keep thinking about its mechanical issues.
Long term, the tight rings bothered
me more than anything else.

So enough about the mechanical aspects, how did the 8" f/4
perform optically? No one expects optical perfection from an inexpensive
f/4 reflector, and you don't get it here. The star test showed moderate
spherical aberration (overcorrection.) The secondary obstruction is rather
large at around 35%. At low power, even Naglers and Panoptics couldn't
quite correct the coma at the edges of the field of view. Don't use cheap
low power eyepieces with this scope! However, once you get the power up
over 60X or so (with a 13 mm Type 6 Nagler in my case) the distortion at the
edges goes away and you can enjoy the view. You're naturally going to seek
out large deep sky objects with a scope like this, and I immediately went for
M31, the Double Cluster, M33, and the Pleiades. The scope did not
disappoint. Many amateur astronomers are used to seeing wide fields or
bright images, but it's that that often that you see wide fields and
bright images. As long as you don't look too hard at the edges, you can
convince yourself that you've got a really, really bright Pronto. This can
get addicting.

The scope was acceptable on double stars. Albireo was
nice, as was gamma Aries. Eta Cass showed its deep red component, but the
split wasn't totally clean. On Jupiter, the views started to break down
around 125X - not a great sign. I figured the conditions weren't good that
night, but a nearby C102F fluorite refractor showed us otherwise, providing
crisp separation on the doubles and clean detail on Jupiter.

Looking down the tube

I should mention the finder, which was a nice surprise.
I've gotten used to throwaway finders on cheap scopes, but the 8X50 unit on the
scope was really nice. The crosshairs are just wide enough to be useful
without intruding on the views, and optically it was sharp to the edge.
Under magnitude 4.5 skies, I had no trouble seeing the Dumbbell, M31, NGC 457,
and even M15 in it.

Visual observing is only half the of the utility with this
scope. I'm not an expert astrophotographer, but I did manage to take some
quick shots through the Orion. Here, the telescope was clearly more in its
element. I learned to appreciate the focuser, which is an unusually nice
unit given the scope's price. Its long focus travel accommodated
everything I threw at it. For prime focus, you remove the 2"
extension tube. While using my Celestron NexImage webcam, the extension
tube goes back in. If I was using a barlow, the same tube either goes in,
or stays out, depending on what kind I was using. The Crayford mechanism
is very smooth and the tension is adjustable. The barrel is marked so you
can quickly dial in common focus positions, a real time saver. The
focuser, coupled with the tack-sharp finder, made life easy when taking images.

I didn't have the conditions or the equipment to try any deep
sky photography, but owners of this scope have told me it is OK for long
exposure imaging. All of them, however, have told me that the Paracorr is mandatory.

I enjoyed my time with the Orion 8" f/4 OTA. I did
feel that it was more suited for imaging and that its visual utility was
just a nice bonus thrown in. We had a stretch of fine, clear weather at
the end of November and the telescope kept me up, both at night and early in the
morning (there's nothing quite like getting up at 4 AM in 18 degree weather!)
for close to a week. I had to catch up on some sleep before I could muster
the energy to write this review. Hey, if that's not an endorsement, what
is?

Orion 8" f/4 Newtonian Astrograph Hots

Focuser to die for

Jack of all trades, leans towards imaging

Good quality finder

Attractive price

Orion 8" f/4 Newtonian Astrograph Nots

For visual observers, the scope leans towards imaging

Minor mechanical issues detract from seamless observing
experience

Critical observers may not appreciate so-so optics, needs a Paracorr for optimal performance

Verdict

A great deal for budget-minded imagers who dabble in visual observing.